This invention relates generally to imaging systems and more particularly to methods and apparatus for processing a fluoroscopic image.
In at least some known imaging systems, a radiation source projects a cone-shaped beam which passes through the object being imaged, such as a patient and impinges upon a rectangular array of radiation detectors.
In some known radiation detectors, such as those including thin film transistors (TFTs) and photodiodes, a “lag” signal may occur. Lag is a dependence of an image signal due to the past exposure history. Some known medical applications require a transition from a high radiation dosage exposure to a fluoroscopic mode, which uses a low radiation dosage exposure. A lag signal from the high radiation dosage exposure may introduce artifacts into the fluoroscopic images in the form of ghost images of the high exposure image.
For example, detector lag can occur when an x-ray imaging system is switched from a high dose exposure application, such as Cine Record (Record), Digital Subtraction Angiography (DSA), and Radiography (RAD), to a low dose fluoroscopy (Fluoro) in a relatively short period. Additionally, at least one clinical study has shown that lag can persist in a Fluoro sequence for up to approximately several minutes. Accordingly, lag residue also facilitates reducing a dynamic range of an x-ray signal and a signal contrast.